1. Field of the Invention
The present invention relates to a permanent magnet type rotating machine employing permanent magnets as field magnetic poles.
2. Discussion of Background
FIGS. 34 through 36 are diagrams showing a magnet fixing device of a conventional small-sized motor disclosed, for instance, in Japanese Examined Utility Model Publication No. 38733/1973, wherein FIG. 34 is a partially broken front diagram, FIG. 35 is a partially broken side diagram of FIG. 34, and FIG. 36 is a diagram showing an elastic fixing plate 10 in FIG. 35.
In FIGS. 34 through 36, reference numeral 1 designates a motor housing (yoke), to an end portion of which a bearing metal 2 is press-fixed by a press-fixing plate 3. Numeral 4 designates a plurality of fixing pieces which are cut out to the inner side of the motor housing 1, each of which is provided with an angle .alpha. to retain ones of tapered portions 7 and 8 which are formed at both ends of arcuate magnets 5 and 6. The inner diameter B of the fixing piece 4 is formed larger than an inner diameter C which is formed by the arcuate magnets 5 and 6. Numeral 9 designates protrusions which are protruded to the inner side of the motor housing 1, for positioning the arcuate magnets 5 and 6 in the circumferential direction. Numeral 10 designates a ring-like elastic fixing plate, which is formed by an elastic material such as steel plate for spring and phosphor bronze plate for spring, at the inner side of which a plurality of press-fixing claws 11 are provided for retaining the other tapered portions 8 of the arcuate magnets 5 and 6, and at the outer diameter portion of which a plurality of fixing claws 12 are provided for fixing the elastic fixing plate 10 to the housing 1 in press-fitting the elastic fixing plate 10 to the motor housing 1 in a press-fitting operation. Further, the fixing claw 12 is inclined toward the outside of the magnet by an angle of 8 with respect to a plane 13 of the elastic fixing plate 10. The outermost diameter D of the fixing claw 12 is formed slightly larger than the inner diameter A of the motor housing, and the inner diameter E thereof that is the same with the inner diameter of the press-fixing claw 11, is formed larger than the inner diameter C of the magnets 5 and 6.
An explanation will be given of the integrating operation of the magnet fixing device in the above construction. First, the bearing metal 2 is press-fixed to one end portion of the motor housing 1 by the press-fixing plate 3. Next, the arcuate magnets 5 and 6 are inserted to the inner diameter portion of the motor housing 1 along the positioning protrusions 9. Then, the tapered portions 7 are retained by the fixing pieces 4. Further, the elastic fixing plate 10 is finally press-fitted to the inner diameter portion of the motor housing by a pertinent pressure, and the press-fitting is stopped when the press-fixing claws 11 apply a pertinent pressure on the tapered portions 8 of the magnets 5 and 6.
As stated above, in the conventional permanent magnet type rotating machine, the permanent magnets 5 and 6 are fixed in the axial direction by the elastic fixing plate 10 which has been press-fitted and fixed in the yoke 1. Accordingly, the elastic fixing plate 10 for fixing the permanent magnets 5 and 6 in the axial direction is necessary as an additional member, which increases the number of parts and increases the production cost.